In Path of Exile, this is probably the single most asked question simply due to inexperience when running lab. Each day the lab resets the layout changes, this means silver keys, silver doors, darkshrines etc all move to a random location. Some days it’s easy enough to hit majority of the shrines/gauntlets/silver doors but on other days it will be harder to do so.
If you have a gold door, izaro and silver doors along the main path. This is a great example of a lab you can run and get a nice chunk of loot especially with the newly buffed quantity silver chests! Unlike buy chaos orbs, so to maximise our profits but lower the amount of time spent within lab we are aiming to do rooms;
- Collect the Shrine, collect silver key.
- Complete Gauntlet (If curious Lockbox).
- Complete Gauntlet (If curious Lockbox) and collect Gold key.
- Collect Silver Key (If room 1 was skipped), complete Gauntlet (If curious Lockbox). and then proceed through gold door.
- Collect Silver key.
- Kill Argus.
- Proceed to Aspirants Trial.
- Argus is generally always worth killing because he has a 100% chance to provide you with an extra Treasure key.
- Open Silver Door.
- Open Silver Door.
- Finish lab.
So this is basically what you are looking to do, hit everything that is on the main path without sidetracking too much, avoiding side rooms which have no real benefit and will only slow your lab times down. A reasonable time for most lab farmers will be around the 5 minute mark which will include all if not most of the possible key drops, you are basically aiming to achieve at least 5/7 keys per run with little effort.
It is also worth noting that things will not always spawn within the same area each time you enter lab, there are 3 places within a room which the different path of exile items can spawn.
I won’t tell you how to identify each one as I would be here for a much longer time, that will come down to experience and time you will notice some rooms have certain layouts upon entering which will allow you to make a quick decision on which direction to head to obtain said object.
But on seconds thought I can at least give a short explanation, so for example in the lab I’ve based the above statement on, the first room has a Shrine and silver key. My first route is bottom right to see if the Shrine spawns there if it has I know the silver key is up and to the left a little, if not it’s in it’s sister spawn.